Moshe fulfilled his mission and the following morning, on the 3rd day of Sivan, he hiked back up Mount Sinai to personally deliver the good news to HaShem (even though HaShem already knew, since He knows everything!)
HaShem responded, “Moshe, I want you to be the middleman. You will be the one who will hear the Ten Commandments from Me, and you will then deliver them to Bnei Yisrael.”
Once again, Moshe relayed the message to his people, but they were not happy with this.
“No, Moshe. We respect you and we certainly want HaShem’s precious Torah.”
“But we want to hear it directly from HaShem – the King of the universe!”
The next morning, on the 4th of Sivan, Moshe climbed the mountain again and delivered the message of his people, “Your wonderful nation wants to hear the commandments directly from You, in Your voice… the voice of the King!”
“Not so fast,” answered HaShem. “If they desire to hear My voice, they must make the proper preparations. They must spend the next two days preparing to become very, very holy people. Tell them to ritually wash themselves and their clothes. Also, make a fence around the mountain so Bnei Yisrael will not get too close to it. Warn them not to touch it at all, since it is holy. On the 6th day of Sivan, I, HaShem, will descend on Mount Sinai and give the Jewish nation the Torah!”
Moshe went right back down and told the people the good news. They prepared and purified themselves so they would be ready for Matan Torah – the giving of the Torah.